Test changes to Actually Portable Python (#240)

- Add missing `os.pipe` and `os.getuid`
- Commented out _dummy_thread from Lib/threading.py so tests
  don't simulate multi-threading and waste time/error out
- Revert test_hashlib to avoid blake2

third_party/python/Lib/threading.py

@@ -1,7 +1,10 @@
 """Thread module emulating a subset of Java's threading model."""
 
 import sys as _sys
-import _dummy_thread as _thread
+import _thread
+# if you REALLY need threading for ensurepip or something
+# use _dummy_thread below instead of _thread
+# import _dummy_thread as _thread
 
 from time import monotonic as _time
 from traceback import format_exc as _format_exc